I added 2 small engineers about two wks ago to my tank and I assumed they would have swam to the bottom of the tank and found some hiding spots n stayed there( that's the type of behavior I've always seen in other tanks)but have not done so...they r always out swimming all over the tank and even at the top near the waterline. This isn't a complaint just wondering if anyone else has ever seen this or did I get a cool pair?